US HB4042

Requires states to reimburse the federal government 100% of costs when the President determines that a National Guard deployment to that state resulted from state government action or negligence

President must provide determination to the Governor within 30 days of concluding the deployment, after which federal funds to the state will be reduced by the amount of deployment costs

Authorizes presidential waiver of reimbursement for states experiencing extreme financial hardship or when deployment primarily protects federal property or enforces federal law

Amends Section 12406 of Title 10, U.S. Code, which governs when the President may call National Guard into federal service (foreign invasion, rebellion, or inability to execute federal laws with regular forces)

Takes effect retroactively on June 1, 2025, applying to all National Guard deployments required after that date